Appliances that open cans are well known in the art. Generally, these can opener appliances include a traction wheel and a cutter wheel. The traction wheel biases the top surface of a can against the cutter wheel, which cuts through the top lid of the can. The traction wheel also acts to drive the can opener appliance around the top of the can, thereby cutting through the can all around the circumference of the can.
One type of can opener appliance cuts through and removes the top lid of the can by piercing and cutting through the lid to gain access to the contents of the can. The main problem with this type of can opener is that the cut edges, both of the cut lid that is removed after the cutting operation and of the body of the can itself, are sharp and thus may be dangerous to the consumer. Another problem is that an unsanitary cutter may come into contact with the contents of the can, and if the cutter is not particularly sharp, the cutter wheel may form small shavings that can contaminate the contents of the can. Additionally, if the entire circumference of the top lid of the can is cut, then the cut lid may fall into the can, thereby also contaminating the contents of the can. Furthermore, it may be difficult and/or messy for the operator to remove the cut lid from the contents of the can.
To address these problems, can opener appliances have been developed that are designed to separate the outside seam of the can and leave non-sharp edges. Examples of these can opener appliances include U.S. Pat. No. 3,719,991, issued to French; U.S. Patent No. Reissued 27,504, issued to Smith; U.S. Pat. No. 1,935,680, issued to Von Wolforsdorf; U.S. Pat. No. 4,782,594, issued to Porucznik et al.; and U.S. Pat. No. 3,510,941, issued to Fyfe. In this manner, the appliance cuts the can at the seam where the top of the can is folded and welded to the cylindrical body of the can during the manufacture of a can (after the contents have been placed into the can). Because the can is cut at the seam, the cut edges, both of the body of the can itself and of the top of the can, are smooth and do not present a hazard for the consumer.
The patents cited above use a pin sliding in an arcuate slot for engaging and locking the can opener appliance on the can to be opened. While these locking arrangements work adequately, over time there is a tendency for the moving parts to wear. The result of this wear is that the engaging and locking function of the appliance is impaired, leading to difficulty in cutting through the can and keeping the appliance in position on the can.
Improvements on the above can opener appliances include U.S. Pat. Nos. 5,121,546 and 5,367,776, both issued to Chong. In the Chong patents, the can opener appliance includes thrust surfaces and a separating means that can be introduced between the separating means. The separating means, typically a ball bearing and stacked ring, is introduced between the thrust surfaces, typically springs, to move a moveable thrust surface away from a fixed thrust surface to separate the traction wheel and the cutter wheel. By this means, the can opener appliance is brought to the cutting position, and the cutter wheel is utilized to cut through the can.
There have been difficulties in producing a can opener appliance that has a side cutting mechanism that is also assisted by an electric motor. All of the patents cited above, except the Porucznik et al. patent, are directed to side-seam cutting can opener appliances which are driven by manually turning a key connected to a traction wheel. It has now been found the side cutting mechanism as disclosed in the Chong patents can be modified to work effectively with an electric motor to provide an electric can opener appliance.